1. Field of the Invention
The present invention relates generally to healing of wounds and wound-treatment therapies. More particularly, but not by way of limitation, the present invention relates to systems and methods for improving fluid-instillation and negative pressure wound therapy (NPWT) apparatuses and methods.
2. Background Information
Clinical studies and practice have shown that providing a reduced pressure in proximity to a tissue site augments and accelerates the growth of new tissue at the tissue site. The applications of this phenomenon are numerous, but application of reduced pressure has been particularly successful in treating wounds. This treatment (frequently referred to in the medical community as “negative pressure wound therapy,” “reduced pressure therapy,” or “vacuum therapy”) provides a number of benefits, including faster healing and increased formulation of granulation tissue. Typically, reduced pressure is applied to tissue through a porous pad or other manifold device. The porous pad contains cells or pores that are capable of distributing reduced pressure to the tissue and channeling fluids that are drawn from the tissue. The porous pad may be incorporated into a dressing having other components that facilitate treatment
Typical instillation therapy instills fluid into a wound under a low positive pressure. For maximum therapeutic effect, the instilled fluid should reach all exposed tissue surfaces. The practice of fully filling a wound with instillation fluid, combined with the application of porous wound fillers and negative pressure to help distribute fluid, are techniques used to try an achieve good instillation therapy. Such techniques include numerous disadvantages. For example, filling a wound with fluid is wasteful, particularly where expensive fluids (e.g. antibiotics) are used as the bulk of the fluid enters the dressing (e.g., a foam) to enable the surface of the wound to be ‘coated’ with instillation fluid.
Even where the instilled fluid is inexpensive, large volumes of fluid may be involved, requiring frequent canister changes that may lead to user dissatisfaction. Although low positive pressures are typically used to fill the wound cavity, the hydraulic (essentially incompressible) nature of the fluid means that over filling can quickly cause drape leakage. Tortuous contours within a wound cavity may be difficult to reach with both foam dressings and liquid-fill techniques as gas pockets may be created. Applying a low vacuum during liquid instillation (to help maintain a seal and reduce leaking, to minimize patient discomfort, and to aid fluid distribution) can be problematic as instilled fluid may be removed before it is fully distributed through the dressing.
For at least the reasons described above, improved wound treatment systems and methods are therefore desired.